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Posher version? - https://www.variotherm.com/en/heating-and-cooling/walls-heating-and-cooling.html

This BBA certificate says yes, section 7.2 page 7. https://www.celotex.co.uk/assets/5405_pitched-roofing_bba-certificate_nov2018.pdf The quality of the tape will be important.

30°, particularly in summer, allows southerly (noon) sun to come 'over the top' while 60° hides the PV surface until later in the afternoon

@Russell griffiths Adding 20mm of PIR to a build up with a U-value of 0.14 reduces it to U = 0.124. A reduction of 0.016 will save (very) much less than 1kWh/m2/year.

Yes, adding insulation suffers from diminishing returns. e.g. doubling the thermal resistance of a building element halves the heat loss, doubling again to 4x original thermal resistance reduces heatloss to 0.25 of original value. So adding twice as much insulation in the second doubling than in the first doubling saves only half as much.

Do you have the thermal resistance (R-value)/U-value of the original build up?

If by 'efficiency' you mean heat output then for a given input temperature a higher flow rate will mean a higher exit temperature because of a lower residence time in the radiator and thus a greater output because the mean temperature of the radiator will be higher. The converse applies for lower flow rates.

The difference is insignificant. However there is a more serious consideration. Whenever insulation is between rafters allowance must be made for the thermal bridging effect of the timber which is significant. Normally the timber is assumed to be 15% by area and the layers in which the celotex 70/60mm are used between rafters have thermal resistances of 1.832/1.570 respectively.

Not because the CO2/kWh has gone down. SAP is a cost index and is not affected by the emission rate, also it should be calculated using the version of SAP in force when you got PP.

These should be cheap :- cut with scissors! http://www.elastolith.nl/en/diy/diy-verwerking/

@passivhybrid your breather membrane has quite a high Sd value relative to your insulations, do you get condensation when you simulate your full build-up with breather membrane? here is a breather membrane with a lower Sd value https://novia.co.uk/uploads/components/variation/NoviaBlack19-5cc2d6b10e0c1.pdf

@passivhybrid, if you did not know about mu values you may find the attached pdf useful. Do you have name/characteristics of your breather membrane? Vapour_Resistances includes perm conversions.pdf

FWIW I think you need something under the PIR to support its edges and to spread any load (roofers) from above as it would concentrate at the 250mm joists. Why have a 150mm gap above the plasterboard? Fill with frametherm32 (or cheap loftroll) and use less/no PIR.

Some products, https://www.lunos.de/en/systems/ http://www.utilityfreeliving.co.uk/heat-recovery-ventilators/ https://renergise.ie/shop/energy-saving-products/ventilation/

I was thinking you were putting the Phenolic between the joists like normal 'loft roll'. Putting the foil on the warm side would eliminate the possibility of interstitial condensation within the board. This would also apply to your suggested build-up

Just make sure the foil is on the warm side of the board and no other insulation below it

No, but this may be of interest, although they may not do retail. https://keldatechnology.com/

So at what thermal conductance ( or other definition) does a material become an insulation requiring use of Table 52.2?

Do they actually mean 'less than' or are their other values for more insulating insulation?

According to this site - https://www.bauen.lt/keraminis-blokas-wienerberger-porotherm-44-p-s the blocks have thermal conductivity of 0.16W/m.K and thus a 440mm block would require at least 100mm PUR/PIR to reach the maximum Passivhaus U-value Given the actual shape of the blocks do they have the same thermal conductivity in both horizontal directions?

How about Orcon F? https://www.ecomerchant.co.uk/pro-clima-orcon-f-adhesive.html https://proclima.com/products/bonding-agents/orcon-f

I would use the full inside air/outside air temp difference for the floor as the full heatloss path is floor-soil-outside air. Allow about 30% of fabric heatloss for thermal bridging. Ventilation heat loss is Volume of structure (m3 ) x air changes per hour x temperature difference (°C) x 0.3 Watts Remember you are an 80W heat source and the office equipment will contribute The size of the heater will more likely be determined by providing a reasonable heat from cold performance than steady state loss. So a 2kW fan heater will probably do.

You do not have to. Just make sure you have a heating system capable of providing the design heat loss plus about 3kW for water heating.

Some turbines have a suction tube below the 'spinning bit' and strictly speaking the head is from the top of the reservoir down to the unconstrained water escaping from the turbine. With a small head you are probably looking at some sort of cross-flow turbine or just possibly a Poncelot 'wheel' (I kid you not ?) Examples of both here http://www.waterwheelfactory.com/history.htm

The theoretical output in Watts is mass per second (in kg, effectively litres/sec for water) x gravity (9.81m/s2) x head (in metres). The electrical efficiency of hydro at the kW scale is about 50% for good turbines. So with a 0.5m head you would need around 400litres/sec of flow for a 1kW output.